1. Technical Field
This application generally relates to data storage, and more particularly to techniques used in connection with verification of devices in a data storage system.
2. Description of Related Art
Computer systems may include different resources used by one or more host processors. Resources and host processors in a computer system may be interconnected by one or more communication connections. These resources may include, for example, data storage devices such as those included in the data storage systems manufactured by EMC Corporation. These data storage systems may be coupled to one or more host processors and provide storage services to each host processor. Multiple data storage systems from one or more different vendors may be connected and may provide common data storage for one or more host processors in a computer system.
A host processor may perform a variety of data processing tasks and operations using the data storage system. For example, a host processor may perform basic system I/O operations in connection with data requests, such as data read and write operations.
Host processor systems may store and retrieve data using a storage device containing a plurality of host interface units, disk drives, and disk interface units. Such storage devices are provided, for example, by EMC Corporation of Hopkinton, Mass. and disclosed in U.S. Pat. No. 5,206,939 to Yanai et al., U.S. Pat. No. 5,778,394 to Galtzur et al., U.S. Pat. No. 5,845,147 to Vishlitzky et al., and U.S. Pat. No. 5,857,208 to Ofek. The host systems access the storage device through a plurality of channels provided therewith. Host systems provide data and access control information through the channels to the storage device and storage device provides data to the host systems also through the channels. The host systems do not address the disk drives of the storage device directly, but rather, access what appears to the host systems as a plurality of logical disk units. The logical disk units may or may not correspond to the actual disk drives. Allowing multiple host systems to access the single storage device unit allows the host systems to share data stored therein.
Data storage systems may perform techniques in connection with verifying that one or more devices included therein are physically accessible for obtaining data. These techniques may be referred to as disk or device scrubbing techniques that may be performed to ensure that data on the devices is accessible when needed in connection with processing received I/O operations. Existing device scrubbing techniques may not perform scrubbing operations within an acceptable time period. As a result, media faults may not be discovered in a timely fashion. Existing techniques may also not be flexible to allow for variations in device scrubbing in accordance with each device. Additionally, existing device scrubbing techniques may not acceptably balance device scrubbing with other operations performed by the data storage system.
Thus, it may be desirable to utilize a flexible device scrubbing technique which provides for increased device reliability. It may also be desirable that the technique balance scrubbing operations to reduce adverse effects on other data storage system operations.